is mark wearin a wig for the movie? or did he actually grow his hair out that long? hmmm well if neone knows, just reply plz, i've been so curious ever since i've seen it (by the way, its such a great movie)

Director Steven Herek said there were some scenes Mark did wear a wig.
For example, He was wearing a wig at the scene Chris and Emily were in the Church for practicing chorus of choir.
I heard that from DVD's director commentary.

I don't know about all of you......but i could have sworn that he had hair extentions. A matter of fact i think some others in the movie were wearing hair extentions as well. To me it looked so obvious that he was wearing hair extentions.

The answer is neither one. He had hair sewn to his real hair. He was a scared that if he had a wig on it might fall off during his running and jumping on stage. At the start and very end of the movie where you see him with short hair that is his real hair.

OK. I think of it this way. If he was in the middle of shooting the Perfect Storm and researching the stuff as possible. He wouldn't have time to grow it out on such short notice because he had short hair in the Perfect Storm. So that eliminates that he grew it out as long as it was in the movie when he had the long long hair. So he either wore a wig or hair extentions. So prolly he used hair extentions for when he was on stage and wore a wig when like when he was walking to the bus when that guy let Jennifer Aniston know that she could go on the bus and in the studio. But at the end of the movie he grew it out to that point.